Medullary thyroid cancer with ectopic Cushing's syndrome: A multicentre case series

[~MaryO~]

First published: 06 November 2021

https://doi.org/10.1111/cen.14617

 

Abstract

Objective

Ectopic Cushing′s syndrome (ECS) induced by medullary thyroid cancer (MTC) is rare, and data on clinical characteristics, treatment and outcome are limited.

Design

Retrospective cohort study in three German and one Swiss referral centres.

Patients

Eleven patients with MTC and occurrence of ECS and 22 matched MTC patients without ECS were included.

Measurements

The primary endpoint of this study was the overall survival (OS) in MTC patients with ECS versus 1:2 matched MTC patients without ECS.

Results

The median age at diagnosis of ECS was 59 years (range: 35–81) and the median time between initial diagnosis of MTC and diagnosis of ECS was 29 months (range: 0–193). Median serum morning cortisol was 49 µg/dl (range: 17–141, normal range: 6.2–18). Eight (73%) patients received treatment for ECS. Treatment of ECS consisted of bilateral adrenalectomy (BADX) in four (36%) patients and adrenostatic treatment in eight (73%) patients. One patient received treatment with multityrosine kinase inhibitor (MKI) to control hypercortisolism. All patients experienced complete resolution of symptoms of Cushing's syndrome and biochemical control of hypercortisolism. Patients with ECS showed a shorter median OS of 87 months (95% confidence interval [95% CI]: 64–111) than matched controls (190 months, 95% CI: 95–285). Of the nine deaths, four were related to progressive disease (PD). Four patients showed PD as well as complications and comorbidities of hypercortisolism before death.

Conclusion

This study shows that ECS occurs in advanced stage MTC and is associated with a poor prognosis. Adrenostatic treatment and BADX were effective systemic treatment options in patients with MTC and ECS to control their hypercortisolism. MKI treatment achieved complete remission of hypercortisolism and sustained tumour control in one treated case.

 

1 INTRODUCTION

Medullary thyroid cancer (MTC) arises from calcitonin-producing parafollicular C-cells of the thyroid gland and accounts for 2%–5% of all thyroid malignancies.¹ In about 25% of cases, MTC occurs in a hereditary manner as a part of multiple endocrine neoplasia type 2 (MEN2) caused by oncogenic germline REarranged during Transfection (RET)-mutations. Up to 65% of patients with the sporadic disease have somatic RET-mutations, among which RETM918T is the most common and associated with adverse outcome.^2-5 At diagnosis, cervical lymph node metastases are present in about half of patients and distant metastases in around 10% of MTC patients.⁶ While the localized disease has a 10-year disease-specific survival (DSS) of 96%, 10-year DSS is only 44% in cases with distant metastases.^7-9

Besides calcitonin and carcinoembryonic antigen (CEA), C-cells may also ectopically secrete corticotropin-releasing hormone (CRH) or adrenocorticotropic hormone (ACTH). Cushing's syndrome (CS) due to ectopic CRH or ACTH secretion induced by MTC is rare and data on clinical characteristics, treatment and outcome are limited and mostly from case studies. In a retrospective study of 1640 adult patients with MTC, ectopic Cushing's syndrome (ECS) due to ACTH secretion was reported in only 0.6% of patients, whereas previous studies reported a higher prevalence, possibly due to selection bias.^10-12 ECS mostly occurs in metastatic cases and significantly impairs prognosis: around 50% of the mortality in patients with ECS has been attributed to complications of hypercortisolism.¹² Diagnosis of ECS is difficult and includes a combination of clinical assessment, dynamic biochemical tests (e.g., 24 h urinary-free cortisol, midnight salivary cortisol, 1 and 8 mg dexamethasone suppression test), inferior petrosal sinus sampling (IPSS) and multimodal imaging.¹³

This retrospective study aims at describing clinical characteristics, treatment and prognosis of 11 patients with MTC and ECS at 3 German and 1 Swiss tertiary care centres and to illustrate effective treatment in this ultrarare condition.

2 PATIENTS AND METHODS

2.1 Setting

This registry study was conducted as part of the German Study Group for Rare Malignant Tumours of the Thyroid and Parathyroid Glands. Data were obtained from records of patients diagnosed with MTC between 1990 and 2020 and concomitant ECS diagnosed between 1995 and 2020 in three German and one Swiss tertiary care centres. All patients provided written informed consent and the study was approved by the ethics committee of the University of Würzburg (96/13) and subsequently by the ethics committees of all participating centres.

2.2 Data acquisition

Eligible patients were 11 adults with histopathological evidence of MTC and the diagnosis of ECS at initial diagnosis (synchronous CS) or during the course of disease (metachronous CS). This group was matched with 22 patients with histologically confirmed MTC without evidence of ECS by sex, age at MTC diagnosis (±5 years), tumour stage and calcitonin doubling time (CDT).

The diagnosis of ECS was established by standard endocrine testing according to international guideline recommendations,¹⁴ local good clinical practice procedures and laboratory assays in participating centres. The primary endpoint of this study was the assessment of overall survival (OS) in MTC patients with ECS from the date of MTC-diagnosis and the date of ECS-diagnosis versus matched MTC patients without ECS (1:2 ratio). The secondary endpoints were assessment of progression-free survival (PFS) and efficacy of multityrosine kinase inhibitors (MKIs) treatment (based on routine clinical imaging in analogy to RECIST 1.0 and 1.1). Treatment and follow-up of patients were performed according to the local practice of participating centres. Efficacy was assessed locally by imaging (positron emission tomography/computed tomography [PET/CT], CT, magnetic resonance imaging [MRI] of the liver and bone scintigraphy) and measurement of serum calcitonin and CEA levels every 3–6 months. Clinical data were recorded by trained personnel at all sites. Tumour stage was defined according to the American Joint Committee on Cancer TNM classification, seventh edition,¹⁵ based on clinical and histopathological assessments.

2.3 Statistical analysis

PFS and OS probabilities were estimated using the Kaplan–Meier method. The log-rank test was not used to test the difference between the study group and the control group due to the paired sample design. For the comparison of nonnormally distributed data, we used the Mann–Whitney U test. p Values less than .05 were considered statistically significant. Statistical analyses were performed with SPSS Version 26 (IBM).

3 RESULTS

3.1 Clinical characteristics of patients with ECS

Eleven patients (five male and six female) with histopathological evidence of MTC with ECS in three German and one Swiss tertiary care centres were included. Twenty-two controls with histologically confirmed MTC without the diagnosis of ECS matched by sex, age at MTC diagnosis (±5 years), tumour stage and CDT were enroled. Baseline clinical characteristics of the study population and the control group are shown in Table 1. In patients with ECS, median follow-up from initial MTC diagnosis was 6.3 years (range: 0–17) and median follow-up from diagnosis of ECS 7 months (range: 0–110). Median age at initial diagnosis of sporadic MTC was 45 (range: 31–67, n = 7) and 52 years (range: 35–55, n = 3) for patients with germline RET mutant MTC.

 

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